If you’ve ever worked with a research company or a panel provider on a project, one of the first questions they’re going to ask you is — “What’s the incidence rate of the audience?”
Everyone from brand managers to savvy researchers at some point has asked for a clear definition or even a calculation method for incidence rate (IR). For market researchers, a clear grasp of IR can streamline the recruitment process, enhance data quality, and ultimately lead to more accurate and actionable insights. Let’s start by exploring exactly what IR means and the key factors that influence it.
What is incidence rate and why does it matter?
Incidence rate in market research is a measure of a particular population's occurrence rate within the larger population. It’s represented as a percentage, showing people within a given sample who are eligible to participate in a study. In simple terms, IR is used to convey the size of a population.
IR plays a key role in study design and execution. For anyone conducting research, IR can help them better understand the size and characteristics of their qualifying audience, while for a research company or panel provider, it’s an important cost and feasibility indicator.
Below are some key areas where incidence rate plays a crucial role:
Cost and Field Timeline
A lower IR typically means higher costs and longer field times, while a higher IR can make recruitment more cost-effective and efficient. For example, if IR were 100%, that would mean that the entire population is eligible — essentially an easier audience to interview like the general population. On the other hand, if you had an IR of just 5%, then only 5% of the total population meet the criteria for that audience —a much smaller or niche audience that is going to be more difficult to reach. To interview this group and get a robust minimum base size, you might have to collect a lot more samples thereby extending field time.
Data Quality
A high IR can yield higher quality data. For example, when a sample closely reflects the target population, the insights generated are more reliable, reducing the risk of bias or misrepresentation. Conversely, a lower IR may introduce challenges like higher dropout rates or increased cleaning efforts which can impact the integrity of your research.
Representativeness
A high IR helps ensure your sample reflects the target population, maintaining that research findings are both useful and reliable. It’s essential that the data you collect is representative of real behaviours and opinions. By contrast, a low incidence rate may introduce biases, requiring additional adjustments or weighting to correct for gaps in representation.
Below demonstrates some examples of audiences and their differing IRs. Please note that these are general guidelines. IR changes by factors like location (e.g., country, region, district, etc.) or behaviour (e.g., soda drinkers, remote workers, etc). It can also fluctuate over time.
- High IR (70% to 100%) - General population 100%
- Medium IR (40% to 60%) - Eaten fast food in the past 3 months 40%
- Low IR (10% to 30%) - Households owning cats 30%
- Very Low IR (1% to 5%) - Males ages 18-34% who own a Tesla 1%
Calculating incidence rate
What can you do when you are asked for an IR?
Sometimes you can leverage public demographic data from the Census Bureau or other stats websites for a specific country. Population Pyramid can serve as a useful source. For example, let’s pretend you want to survey Brazilians ages 20 to 34. With publicly accessible data, you can add up all the percentages from those age groups and it gives you an IR of about 23%. However, for unique or special populations, you may not be able to come up with an IR.
When working with a research company, there is often an incidence rate formula or influencing factors. You’ll want to share key information about your project and audience (e.g., must be male, ages 18 to 24, etc.) to get an estimate. Sometimes panel providers can also run a quick poll with your criteria to estimate the IR for that group.
The Profiles team at Kantar calculates incidence rate based on the total number of completes achieved and your screening criteria. And it’s important to note that your screening stringency and question design can further influence IR. Poorly designed screeners can unintentionally filter out respondents who should qualify.
Why is my IR low?
A low IR typically means that fewer respondents qualify for a study based on the screening criteria. This can happen for several reasons, such as overly narrow targeting, strict qualification criteria, too many quotas, or low awareness and engagement with the topic among the general population. For example, if a survey is looking for consumers who use a niche brand, the percentage of qualified respondents will naturally be lower. Additionally, factors like inaccurate feasibility estimates, outdated profiling data, or high dropout rates due to lengthy or complex screening questions can further impact IR.
To address this, the first step is to conduct a thorough evaluation of the data to identify where in the questionnaire respondents are being disqualified. Pinpointing these drop-off points provides valuable insight into why the IR is lower than expected and helps refine your targeting criteria. The Profiles team at Kantar has the expertise to guide you through this process, ensuring your study remains both efficient and effective in reaching the right audience.
How to improve your IR
When the IR changes in the field, costs and timings are ultimately affected. To improve it, you can take a few steps such as altering the qualifying criteria in the survey or changing up the survey design.
Improving the IR requires an in-depth dialogue and can entail changing the original scope of the research. Sometimes, a low IR is simply unavoidable due to the specific subject matter or niche audience you’re targeting. In these cases, it’s important to carefully consider the number of interviews required and assess whether the project is suitable for online data collection. If the target population is too limited or specialised, alternative methodologies or recruitment strategies might be more effective in delivering reliable results.
It is also important to keep in mind that in some cases, the drop in IR is not a design flaw. It can simply indicate that the target population is smaller than originally expected, which is a genuine research outcome.
Below are 3 strategies for managing low incidence rates:
Adjusting Survey Design: Modify the survey design to improve the incidence rate by altering the qualifying criteria, adjusting how panellists are terminated, removing, or adding questions, and changing the way questions are asked. Simplifying screening questions or broadening criteria can help increase the number of qualified respondents.
- Want a second opinion? Request an online survey review from Kantar experts. We'll identify opportunities to boost reliability and respondent engagement while evaluating key factors like length of interview, question language, bias, and question complexity.
Follow Best Practices: In some cases, it’s not so much about altering the screening criteria, but more-so reviewing the survey to ensure its following design best practices. Factor including panellist fatigue, too many grid questions, and mobile optimisation can all have an impact. Incorporating questionnaire best practices from the start can help avoid the need to mid-field.
Targeting the Right Audience: Refine targeting criteria and use effective sampling techniques to ensure the survey reaches the right audience. Focus on specific demographics or behaviours more likely to qualify for the study.
While budget and timing concerns certainly play a part in influencing these actions, it is equally important to weigh the pros and cons of changes. Determining what to adjust takes careful consideration as you do not want to lose any critical aspects to the data results or reporting.
Get the guidance you need
To recap, the general term IR in market research refers to the size of the population or the rate of occurrence of that population shown as a percentage. An understanding of what impacts the IR can help you avoid surprises or changes in scope down the road.
Employing techniques to improve IR, such as refining screening criteria, leveraging targeted recruitment strategies, or enhancing survey design, can significantly impact the success of market research endeavours. By focusing on these aspects, researchers can better align their efforts with the needs and behaviours of their intended audience, yielding more meaningful results.
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